Explosive.



UNITED STATES PATENT OFFICE.

ALEXANDRE MARIN, 0F STOCK HOLM,

nxrnosrvn.

1,293,154. Specification of Letters iatent.

Io Drawing.

To all who m a! may concern Be it known that I, ALEXANDRE JosnrH MARIN, a subject of'the King of the Belans, residing at Stockholm, Sweden, have invented certain new and useful Improvements in Explosives, of which the following is a specification.

Since the discovery of dynamite numerous products have been successively presented as bein more powerful than, or, at least as equa ly powerful as dynamite, and sometimes as possessing superior'qu-alities as regards stability and economy.

The "most important of these products to enter seriously into the front rank against dynamite was compressed guncotton; but its instability, on the one hand, and on the other the deleterious gases of its explosion, neces: sitating the addition of a large quantity of nitrates which diminished its power, preventedits extended use in mines.

Very many explosives were also presented containing chlorates and picrates, but in such a dangerous form that they threw discredit for a long time upon this kind of explosive.

Then appeared the ex losives of H. Sprengel. The most powerf l were liquid, acid and corrosive, very diflicult for practical use. Their appearance was ephemeral. Other explosives produced by the same inventor were solid some with chlorate bases and others with nitrate bases, but they could not gain any ground over dynamite owing to numerous inconveniences, notably: the chlorate explosives had to be prepared upon the spot,

the mixtures of the nitrate base lacked the aptness for detonation, 80c. Improvements followed under the name of Favier explonot deformable under the pressure of the tamping and so to retain a uniform density.

Attempts have been made to compress explosives of ammonium nitrate, but as detonation of these explosives requires very strong detonators it is clear that the greater the compression the more numerous the miss fires. It therefore'results that in practice these explosives maintain a. feeble specific gravity so that it is necesary to have bore holes larger than those required for dynamite. Their excessive hygroscopicity was also a great inconvenience. v

' The progress of the electro-chemist dis closed another kind of explosive. They had for a base ammonium perchlorate mixed with combustible bodies and also explosives. Their power was superior to thatof allother detonating materials preconceived to the extent of explosives based on nitro-glycerin. They had nevertheless a serious disadvantage; their explosion disengaged considerable quantities of hydrochloric acid which in subterranean mines rendered their employment diflicult. They were also very combustible'and became dangerous, if they contained materials strongly nitrated.

I had in the year1899 remarked this great defect of explosives based on ammonium perchlorate and combustible materials or explosives and had succeeded in effecting a remedy in a radical manner by. the addition of an alkaline nitrate capable by its explosive decomposition in the presence of a nitrohydrocarbon of liberating a quantity of alkaline base sufiicient to saturate the hydrochloric acid; but these explosives, like those of the Sprengel type of ammonium nitrate had the disadvantage of being generally powderous and at feeble chargin density. sometimes plastic but then very iflicult to detonate even with the strongest priming.

- Patented Feb. 4, 1919.

Application filed August 6. 1917. Serial No. 184.714.

- An important improvement in this kind of explosive. was to abandon forever the idea of making plastic explosives and to adopt for blasting explosives the compressed form,

but in this which relates particularly to the explosives with a base of' perchlorate of ammonia it is necessary at once to prevent miss fire in detonation due to the com ression, all of them utilizing detonators 0 the same power as those used for dynamite, and at the same time to effect a density of charging as near as possible to that of the last explosive. The problem wasarduous, it has neverthless'been practically solved. I

It is known, as already stated, that the compression, the chief effect of which is to augment the specific gravity of the explosives, has upon the aptness for detonation of the latter an influence more marked in the sense of diminution of this aptness which ends by being completely annulled. The

more a blasting explosive can be compressed without destroying its aptness for detonation the more this explosive will have useful power. In effect, the pressures produced by the gas of the detonation by unity of surface, augment rapidly at the same rate as the speed of detonatlon, proportionately as the volume occupied by the explosive decreases starting from a certain limit variable with the nature of the explosive, the detonation discontinuing in spite of the use of the strongest detonators, there is no more a-deflagration or combustion with slow development of pressure the explosive becoming propulsive instead of being destroyed.

. Attempts have been made to determine by calculation the limited density of free detonation, but the result is only very approximate and even when it refers to well defined chemical substances such as guncotton and nitroglycerin. When the explosive is 001m posed of different substances mixed together .more or less intimately calculation is no longer of any use, experience alone can (letermlne the density at wlnch one may bring by compression a given explosive, without millimeters thick arranged on a false bottom upon a block of cast metal perforated through and through. The only modifica tion used consists in effecting the detonation of the cartridge in contact with the sheet, not directly with the detonator, but by the intermediary of another cartridge of the same explosive brought by compression to the same density and primed with a detonator of a chosen power. The primed detonator was placed in contact end to end with the cartrldge touching the sheet. The one was separated from the other by a space of several centimeters. It is understood that the cartridges used were provided with their envelops of paraffin paper so that, even when they were In 'contactthey were separated by the thickness 'of their envelops. The detonation of the primed cartridges was considered as free, when it communicated the detonation to the second cartridge with a neatness suflicient for the latter to perforate the sheet like a punch.

Composition of explosives tested.

M 2N-B M 3N-T Mixture formed of 47 parts of NH,,G1O and 34 .parts of Na NO 71 '66 Dinitro-benzin- 29 Trinitro-toluene 34 100 100 In order to simplify the description and to render it clear these explosives will be hereinafter designated by their initials.

By compression these explosives were successively brought to specific gravities varying from 1.2 or 1.6 and tested as regards their aptness for detonation under these different densities. One is compelled only to use for these experiments detonators No. '6 similar to those used for dynamite in order that the advantages resulting from the augmentation of the specific gravities of the explosive may not be compensated by the obligation to use a more powerful detonator.

In order to avoid very dangerous explosive powders and to facilitate the compression the explosive mixtures M.2NB and M.3NT are prepared by the wet method. The quantity of water added varies with the power of absorption of water of the explosive mixtures. The. mixtures M.2NB and M.3N-T may only contain 2 to 5 per cent. since'difliculties are encountered during the desiccation in the form of crystalline efiiorescence on the surfae ofthe compressed cartridges.

The results were as follows M 2NB, tested under three 'difierent densities: 1.2; 1.25 and 1.3. At the density of 1.8 the detonation was still effected at the unprimed cartridge, but only if the cartridges were in contact.

M 3N-T, tested at densities varying between 1.45 and 1.6, at the density of 1.6 the unprimed cartridge still detonated if the two cartridges were in contact.

With M 3NT compressed up to a density-of Lathe detonation was reproduced from one cartridge to another even when separated by a space of 20 mm.

Theory indicates for the explosives M 2NB and M 3NT limited densities for free detonation in the neighborhood of 1.46. The experimental results are in complete contradiction to those given.

It is to be inferred from these tests that the limited density for free detonation was in practice limited to a density of about 1.3

' for the explosive M 2N-B, and about 1.6 for M 3N-T.

These results acquired and checked by repeated experiments have been ut to the proof in the same conditions wit mixtures formed from equal arts of the explosives previousl tested, viz:

Explosive M.B.T. formed from equal parts of M.2N-B and M.3NT.

With the explosive compressed to a density of 1.3 detonation occurred at the unprimed cartridge even with a space of mm. between the cartridges. Compressed to a density of- 1.4 no detonation of the unprimed cartridge was obtained with an interval between the cartridges but the detonation was transmitted when the cartridges were in contact.

In conclusion it may be said that, by the mixture of the explosives studied, explosive products are obtained which by compression, i

lose their aptitude for detonation more rapidly than their components.

importance which the question presents of the charging density of blasting explosives recommended to replace dynamite.

The explosive M.3NT has been submitted to special experiments with the object of ascertaining if the increase in the density by compression augments its sensitiveness to mechanical 'shocks and consequently the danger resulting from its manipulationor from its manufacture. It has occurred to the inventor that the shock of the cased bullets of modern military rifles, fired at a short range against an iron plate sufiiciently thick to arrest nearly every shot, may be considered as equal to the most intense shock likely to occur in practice. The explosive cartridges studied brought by compressionto the density at which they can yet detonate freely with detonator No. 6 were inclosed in tin G5 cific gravity of 1.5 it did not detonate. It

has been concluded from the experiments that as regards safety or stability the increase in density obtained by compression had a favorable influence on the explosives in question. The explosive M.3N-T, was tested as regards its'power in an Abel lead cylinder modified accordin to the views of the 5th Congress of Applie Chemistry. B this means there was an enlargement of re c.m.

The more important explosives 'with a base of chlorate and of ammonium nitrate which alone have gained ground over dynamite, such as cheddite and Favier ex losive or ammonite have also been teste in lead cylinders of the same type, produc- Cheddite NO an enlargement of 285 c.m.

Favier explosive No. 1 an enlargement of 295 can.

Nobels dynamite No. 1 gave an enlargement of 300 cm. and gelignite 432 cm.

Of all the explosives presented as capable of supplanting dynamite in mine work, the explosive M.3N-T is one of the most powerful. There is thus established a most serious advance over all the endeavors to replace explosives based on nitroglycerin and guncotton by more stable products.

In addition to the explosive mixtures above mentioned and which constitute in their composition two nitro-hydrocarbons of different origin, I have studied, as re ards the efi'ect of compression on their aptitude for detonation, several other mixtures based on oxidizing salts l TI-I ClO,-{-NaNO additions of a mixture of different nitrated derivatives of the same hydrocarbon, such as the trinitro and tetranitro-napththalene.

I claim 1. A process for producing compressed solid safety explosives detonating freely in the open air with a No. 6 detonator, consisting in mixing armnonium perchlorate, sodium nitrate, and a nitro -hydrocarbon with a small quantity of water and compressing the mixture so as to give it a density of 1.25 to 1.6 after drying, substantially as hereinbefore set forth.

\ 2. A process for producing compressed safety explosives detonating freely in the open air under the explosive shock of a No. 6 detonator, consisting in mixin 66 parts by weight of a mixture formed 0 .47 parts by weight of ammonium perchlorate and of 342 parts by weight of sodium nitrate, with 34 In testimony whereof haire signed my parts by weight of trinitro-toluene, the subname to this specification in the presence of 10- stance being mixed after being humidified two subscribing witnesses.

with 2 to 5 per cent. of water and compressed 5 into any suitable form in such a manner that JOSEPH MARIN the specific gravity of the explosive is be- Witnesses: tween 1.45 and 1.6 and does not exceed this W. HARRIS,

degree after desiccation. J AOOB BAGGE. 

